Air conditioning system



Aug., 1, 195o w L, MCGRATH 2,517,498

AIR CONDITI ONING SYSTEM Filed June 28, 1945 Patented Aug. l, 1950 AIBCONDITIONING SYSTEIK William Loughney McGrath, Syracuse, N. Y., al-

signor to Carrier Corporation, Syracuse, N. Y., a corporation ofDelaware Application June 28, 1945, Serial N0. 602,002

voisins. l

mais invention relates to air conditioning systems and, moreparticularly, to systems in which air is tempered under dillerentoperating conditions by the circulation of heated or cooled water orother fluid through one or more heat exchangers.

ln Carrier Patents Nos. 2,363,294 and 2,363,945, granted November 21,1944 and November 28, 1944, respectively, there is disclosed anairconditioning system in which a volume of air is conditioned to a,desired degree at a central conditioning point, and is then distributedat `relatively high static pressure and at relatively high velocity to aplurality of units respectively disposed in and serving a plurality ofareas or enclosures to be conditioned. The high pressure air supplied toeach unit is discharged therein through nozzle formations or the like,and in this manner induces a relatively great circulation of airwithdrawn from the area served by the unit. The primary or conditionedair and the secondary or induced air are then supplied to the area to beconditioned. The primary air may be conditioned at a centralconditioning point; and more edective and economical operation isachieved by the delivery i heated or cooled water or other huid to thevarious units from a.

central station preferably to eilect sensible cooling or heating oi' aircirculated 'through the units as required.

In such system, it is necessary to supply some form of control toproduce and to maintain desired atmospheric conditions. Carrier PatentNo. 2,342,328, granted February 22, 1944, discloses for this purpose avalve structure capable of reflecting changes in air conditions andcompensating for variations in such conditions during all seasons of theyear. The system so described has been highly successful in commercialoperation.

The chief object of the present invention is to provide a simple andmodified system of this general type. l

an object of the invention is to provide an air conditioning systemembodying improved means of supphfing conditioning medium to a pluralityof air conditioning units disposed in different sones.

A further object is to provide an improved control for an airconditioning unit capable of satisfactory perfomance under differentseasonal op- @rating conditions.

A still further object is to provide an improved control for deliveringcooled or heated conditioning medium, automatically as desired, to oneor more air conditioning units under different seasonal operatingconditions.

A still further object is to provide a watercirculating system operatingunder relatively low pressure to govern the flow of conditioning mediumof certain character through a conti-oli under certain seasonaloperating conditions and in which an imposed pressure may be used whenmedium of other character is employed to change the operation of thecontrol under other .seasonal operating conditions.

This invention relates to an air conditioning system which includes aunit for conditioning air. a supply of conditioning medium. a passagewayor duct for supplying conditioning medium from said supply to said unit,a. second passageway or duct into which conditioning medium passes fromsaid unit, and control means in said nrst passageway responsive to thepressure of the conditioning medium for controlling the circulation ofconditioning medium through the unit. Preferably, means are lprovidedfor imposing a predetermined pressure on the conditioning medium in therst passageway so that a predetermined increase in pressure may beemployed to modify the operation of the control means; under variousseasonal operating conditions.

This invention further relates to an improved control valve for systemsof the character described which comprises, in combination, a. housing,a change-over element disposed in the housing, means lor causing saidelement to assume one position when conditioning medium under apredetermined pressure is fed to the valve and a second position whenconditioning medium. under a diiIerent predetermined pressure is fed tothe valve, a member for opening and closing a passageway from whichconditioning medium is discharged from the valve, and means operativeresponsive to changing conditions in an :area being air conditioned forcausing said member to tend t0 change the amount of conditioning mediumnowing from the valve. Referring to the drawing illustrating a preferredembodiment of the invention,

Figure 1 is a diagrammatic view illustrating the air conditioning systemof the present; invention;

Figure 2 is a sectional view. on an enlarged scale, of the controlmechanism included in the system shown in Figure 1; and

Figure 3 is a diagrammatic view illustrating a modication of theinvention.

Referring to Figure l, there is shown a diagrammatically an airconditioning system including source of supply or receiver I forproviding to the system a desired volume of conditloiilns medium, whichmay be heated or cooled water or other fluid. A pump I sends theconditioning medium to a plurality of air conditioning units 4 throughline 5. One or more units 4 may .be disposed in different zones of abuilding such as a hotel or oiilce building, and usually a number ofthem are placed on different levels or iioors of the building, one ormore units serving each room or area. In Figure 1 three iloors areillustrated on which units 4 are positioned. Control valves 6 aredisposed at each unit 4 or in the branch lines 5' leading to each unitand serve to control the circulation of conditioning medium through theunits. 'A return line I is provided into which conditioning mediumpasses from the various units 4 and by which such medium .preferably isreturned to the source of supply or receiver 2.

A closed expansion tank 8 is disposed in the system to maintain apredetermined pressure upon the conditioning medium in line 5. Thepressure imposed by tank 8 upon conditioning medium in line 5 may bevaried by means of a compressor or pump 9 connected to a changeover lineI8. A thermostat T controls the operation of compressor 8 and may beactuated by means of a thermal responsive element II disposed in or incontact with line 5 and, preferably, positioned on the down stream sideof pump 3, illustrated.

In Figure 2, there is illustrated the preferred control valve 8 employedin the system. Valve 6 comprises a housing I2 enclosing double-seatedvalve poppets I3 and I4. An entrance port I5 is provided at one side ofhousing I2 and an exit port I8 is provided on the other side of thehousing. Separate passageways I l and I8 may be provided through thevalve between ports I5 and I8, cooling medium passing through passagewayI8 and heating medium passing through passageway Il'. The course ofcooling uid is indicated by a dash line while the course of heatingfluid is indicated by a dot and dash line. Poppets I3 and I4 control theilow of fluid through passageways I 'I and I8, as will hereinafter bedescribed. Poppet I3 is actuated by the pressure of the conditioningmedium being fed to the valve while poppet I4 is actuated by thetemperature of the area or space being conditionedboth serving tocontrol the ilow of fluid through passageways I1 and I 8 under differentseasonal and load requirements.

Valve poppet I3 is attached to a bellows I9 and is actuated by expansionand contraction thereof. A spring 20 is provided in housing I2 adaptedto apply a predetermined force or pressure to bellows I9. The pressureor force applied by spring 20 may be adjusted as desired by means of theadjusting screw ZI.

The force applied to bellows I9 by spring 28 depends upon the hydraulicpressure maintained in the system. For example. under winter operatingconditions, the force applied by spring 20 to bellows I8 is greater thanthe hydraulic pressure of the conditioning medium so that poppet I3moves downward seating at the bottom to seal passageway I8 and to openpassageway I'I; under summer operating conditions the pressure appliedto the conditioning medium is greater than the force applied by spring28 so that poppet I3 moves upward seating at the top to seal passagewayI I and to open passageway 28.

Valve poppet I4 operates similarly to poppet I3 but in response to thetemperature of the area being conditioned. A thermostat (not shown) isdisposed in the area being conditioned and is connected to bellows 22 byline 23. A suitable limit regulating control (not shown) is alsoconnected to bellows 22 by line 24. Fluid is disposed in the closedcircuit connecting bellows 22, the thermostat and the limit regulatingcontrol. As the temperature in the area being conditioned rises, theiluid expands, expanding 'bellows 22 while upon a decrease in suchtemperature, the iiuid contracts, permitting bellows 22 .to contract.Such devices are well-known in the art and form no part of my inventionper se. Spring 25 provides a resistance downwardly against poppet I4opposed to the upward expansive force of bellows 22.

Considering the operation of the system under winter conditions, springs20 of valves 8 disposed on different floors or building levels will beadjusted for diiferent hydraulic pressures in line 5. For example,referring to the system shown in Figure 1, spring 20 of the upper valve8 (on the top oor) may be adjusted to resist a hydraulic pressure ofconditioning medium of 15 pounds per square inch; spring 20 of theintermediate valve 8 may be adjusted to resist a pressure ofconditioning medium of 25 pounds per square inch and spring 28 of thelower valve 6 (on the 'bottom oor) may be adjusted to resist a pressureof conditioning medium of 35 pounds per square inch. Thus, assuming thepressure of the conditioning medium is less than the amounts given atthe various iioors, poppets I4 will be moved downwardly by 'springs 20and open passageways I1 through the respective valves for the passagetherethrough of heated conditioning medium.

Depending upon the temperature of the area being conditioned, poppet I4will open or close passageway I 'I to the heated conditioning medium.Assuming the thermal responsive element disposed in the area beingconditioned reilects a cool condition therein, the fluid in bellows 22will be contracted, permitting spring 25 to move poppet I4 downwardopening passageway I'I to the heated conditioning medium and permittingits ilow to the conditioning coils of the various units 4. As thetemperature in the area being conditioned rises, bellows 22 will expand.moving poppet I4 upward against the resistance of spring 25 andpartially or completely closing passageway I1.

Under summer operating conditions, an increase in static pressure ofpredetermined amount is imposed on conditioning medium in line 5 bymeans of compressor 9 and expansion tank 8. Such increase in pressuremust be sufiicient to force the poppets I3 upward against the resistanceof springs 20 thus closing passageways I I and opening passageways I 8.Increase of pressure is controlled by thermostat T operating pressurecontrol P (shown in dotted outline) which actuates compressor 9.Thermostat T is actuated by thermal responsive element I I whichreflects the temperature of conditioning medium in circuit 5. If thetemperature of conditioning medium in line 5 is below a predeterminedpoint, the compressor is actuated to impose increased pressure therein,say 10 pounds greater than under winter operating conditions.

Under summer operating conditions poppet I4 may be actuated to open orto close passageway I8. If the temperature in the area being conditionedreflects a warm condition, poppet I4 is forced upward by bellows 22opening passageway I8. As the temperature in the area being conditioneddecreases, bellows 22 contracts, permitting spring 25 to move poppet i4downward thus closing or partially closing passageway I8. As describedabove, poppets I3 and I4 are` automatic in operation, poppet I3 beingoperable in response to the pressure of conditioning medium in thesystem and poppet I4 being operable in response to the temperature ofthe area being conditioned.

In Figure 3, I have illustrated a modified system generally similar tothe system shown in Figure 1. In the system partially shown in Figure 3,an open expansion tanl: 26 is employed and compressor 9 may beeliminated. The tank 26 is connected to change-over line lil and thepressure imposed upon the conditioning medium in line 5 is determined bythe level of conditioning medium maintained in tank 26. A float valve 21maintains a certain level when under summer operating conditions toimpose require-i pressure on conditioning medium while float valve 28maintains a certain level under winter operating conditions, alsoimposing a predetermined pressure on the conditioning medium differentthan that imposed under summer operating conditions.

While I have described the system as requiring an increase in hydraulicpressure under summer conditions, it will be appreciated that a decreasein hydraulic pressure may be employed under such conditions; in suchcase, the valve 6 may be modified accordingly with the position of thetemperature responsive element being reversed in order that the heatedor cooled conditioning medium may ilow in different paths. Suchmodication is contemplated by my invention and may be made withoutdeparting from the scope thereof.

My invention provides an improved air conditioning system in which achange-over from winter to summer operating conditions is controlled bythe hydraulic pressure of the conditioning medium which flows throughthe conditioning units of the system. The conditioning system is lesscomplicated than systems heretofore used and is at least as economicalin installation and operation costs. The unit controls provided aresimple and actuatable by the pressure of the conditioning medium. Thesystem operates satisactorily under both Winter and summerconditions andmay be modified if desired to provide either heating or cooling in anyseason of the year to various zones with the result that any desiredtempering may take place at any point of distribution.

While I have described a preferred embodiment of my invention. it willbe understood my invention is not limited thereto since it may otherwisebe embodied within the scope of the following claims.

I claim:

l. In a system of the character described. the combination of aplurality of units for conditioning air, a supply of conditioningmedium, a passageway for supplying conditioning medium from said supplyto said units, means for imposing a predetermined pressure on theconditioning medium in said passageway, and a plurality of valves insaid passageway for controlling the circulation of conditioning mediumthrough said units, at least one of said valves including a change-overelement responsive to pressure of conditioning medium entering thevalve, Ireans for changing the pressure imposed on the conditioningmedium in said passageway, means for causing said element to assume. afirst position said element being adapted to assrme a second position inresponse to a predetermined change in the pressure of the conditioningmedium, a device for opening and closing a passageway from whichconditioning medium is discharged from the valve, and means foroperating said devicein response to changing conditions in an area beingair conditioned.

2. A system according to claim 1, in which said device tends to reducethe flow of conditioning medium from the valve when said element is inthe first position and the temperature in the area being conditionedtends to rise above a desired level and is adapted to tend toincreasethe ilow of iluid from the Valve when said element is in thesecond position and the temperature in such area tends to rise above adesired level.

3. In a system of the character described, the combination of aplurality of units for conditioning air, a supply of conditioningmedium, a passageway for supplying conditioning medium from said supplyto said units, a second passageway for returning conditioning medium tosaid supply after it has passed through said units, an expansion tankconnected to said first passageway for imposing a predetermined pressureon conditioning medium therein, means for imposing a predeterminedpressure on conditioning medium in said tank, a valve at each unit foradmitting conditioning medium to the unit, means in each valve forclosing a `port therein under a predetermined pressure of conditioningmedium and opening said port under an increase in said predeterminedpressure of the conditioning medium, and means in each valve responsiveto the temperature of the area being conditioned for metering the volumeof fluid passing through the valve.

4. A system according to claim 3 in which an open expansion tank isemployed, the pressure imposed upon the conditioning medium beingpredetermined by float valves in said tank for maintaining a desiredlevel of conditioning medium therein.

5. In a system of the character described, the combination of aplurality of units for conditioning air, a supply of conditioningmedium, a passageway for supplying conditioning medium from said supplyto said units, a second passageway for returning conditioning medium tosaid supply after it has passed through said units, an expansion tankconnected to said flrst passageway for imposing a predetermined pressureon conditioning medium therein, means for imposing a predeterminedpressure on conditioning medium in said tank and a valve at each unitfor admitting conditioning medium to the unit, said valve comprising achange-over element responsive to pressure of conditioning mediumentering the valve, means for causing said element to assume a iirstposition, said element being adapted to assume a second position inresponse to a predetermined change in the pressure of the conditioningmedium, a device for opening and closing a passageway from whichconditioning medium is discharged from the valve, and means foroperating said device in response to changing conditions in an areabeing air conditioned.

6. In a system of the character described, the combination of Vaplurality of units for conditioning air, a supply of conditioningmedium, a passageway for supplying conditioning medium from said supplyto said units, a second passageway for returning conditioning medium tosaid supply after it has passed through said units, an expansion tankconnected to said rst passageway for imposing a predetermined pressureon conditioning medium therein, means for imposingr a predeterminedpressure on conditioning medium in said tank, and a conditioning mediumow :mimos regulating device at each unit for regulating the circulationof conditioning medium through the units, said device comprising a.iirst valve. means for retaining said valve in a iirst position, saidvalve being movable to a second position in response to an increase inpressure of conditioning medium owing through the valve, a secondvalve,and means responsive to changing conditions in an area being airconditioned for changing the position of said second valve to meter theamount of conditioning medium flowing through the valve.

7. In a system of the character described, the combination of aplurality of units for conditioning air, a supply of conditioningmedium, a passageway for supplying conditioning medium from said supplyto said units, a second passageway for returning conditioning medium tosaid supply after it has passed through said units, an expansion tankconnected to said rst passageway for imposing a predetermined pressureon conditioning medium therein, means for imposing a predeterminedpressure on conditioning medium in said tank, and a control valve ateach unit for regulating the circulation of conditioning medium throughthe units, said valve including a first upper passage, a first lowerpassage, a second upper passage, a second lower passage, means 8 i foradmitting a first conditioning medium to the valve, means operativeresponsive to the pressure of said conditioning medium for causing oneo! said ilrst passages to be open and the other to be closed, secondmeans for causing one of said second passages to be open and the othersecond passage to be closed, and a temperature responsive element foractuating said second means in response to changing temperatureconditions in an area being air conditioned.

WILLIAM LOUGHNEY MCGRATH.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 22,685 Carrier Oct. 30. 19451,769,859 Roberts July 1, 1930 1,979,779 Tobin Nov. 6, 1934 1,990,663Muiily Feb. 12, i935 2,238,689 Locke Apr. 15, 1941 2,292,335 Durbin Aug.4, 1942 2,299,404 Newton Oct. 20, 1942 2,353,889 Giesler July 18, 19442,372,839 McGrath Apr. 3, 1945

